The invention relates to substantive hydrophobic cationic UV-absorbing compounds. More particularly, the invention relates to novel, cationic, non-hydrolysable, non-irritating UV-absorbing bis-quaternary salts of cinnamidoalkylamines which are substantive to fabric, skin and hair. The invention also relates to a process of manufacture of the said compounds and further to their use in hair, skin and fabric care formulations.
The harmful effects of solar UV-radiation on skin are well known. The UV-B (290-320 nm) portion of solar spectrum is largely responsible for erythema (sunburn) and cancer. [M. M. Rieger, Cosmet. Toiletries, 102 (3), 91, (1987); L. Taylor, Skin Cancer Foundation J., 4, (90) (1986)].
Similarly, photodegradative effect of UV-radiation on human hair is well documented. Continuous exposure to sunrays lightens hair color and makes human hair rough, brittle and difficult to comb. UV rays are reported to damage the proteins of cuticles. Prolonged irradiation results in diminished tensile strength due to breaking of disulphide bonds in keratin. [R. Beyak et al, J. Soc. Cosmet. Chem. 22, 667-668 (1971), E. Hoting et al, J. Soc. Cosmet. Chem. 46, 85-99 (1995)].
In addition, UV light is also known to fade colored garments. [P. C. Screws, Text. Chem. Color, 11, 21 (1987); B. Milligan et al, Polym. Degrad. Stab. 10 (4), 335 (1985)].
A number of UV-absorbing compounds like derivatives of salicylic acid, benzophenones, benzotriazoles, cinnamic acid have been used in personal care products. However, all these molecules suffered from a major disadvantage of lack of substantivity. To make this UV-absorbing moieties more substantive, structural modification have been introduced. U.S. Pat. No. 5,427,773 (1995) discloses cationic substantive photofilters based on dimethylamino benzamide whereas U.S. Pat. No. 5,601,811 (1997) describes about cationic photofilters based on cinnamidoalkyl moiety for UV absorption that are water-soluble. High water-solubility is not always desirable for skin care applications due to possible toxic effects associated with long term usage of cosmetics on human skin. In terms of substantivity to the substrates like skin and hair, water-insoluble cationic photofilters were found to have superior substantivity when compared with water-soluble photofilters in rinse-off products.
The main object of the present invention is therefore to synthesise hydrophobic molecules containing most popular cinnamido moiety to provide UV-B absorption and with cationic centre to provide substantivity to skin, hair and fabric and a long alkyl chain to impart conditioning effect.
Thus the present invention provides a novel, substantive, organic-soluble cinnamidoalkylamine quaternary compounds of Formula I, 
wherein
R1 is selected from H, halo, xe2x80x94OH, xe2x80x94NH2, xe2x80x94NO2, xe2x80x94OCH3, xe2x80x94N(CH3)2, alkyl groups containing from 1 to 6 carbon atoms, alkoxy groups containing from 1 to 6 carbon atoms, alkylamino or N,N-dialkylamino groups containing from 1 to 6 carbon atoms;
R2 is selected from hydrogen, alkyl group containing from 1 to 12 carbon atoms;
R3 and R4 are independently selected from benzyl, alkyl group containing from 1 to 12 carbon atoms,
n is an integer from 1 to 6;
R5 is selected from an alkyl group containing from 8 to 22 carbon atoms; alkenyl groups containing from 8 to 22 carbon atoms;
R7 is selected from bromo, chloro, nitro, methyl and ethyl groups.
A preferred compound of Formula I is, p-methoxy cinnamidopropyl dimethyllauryl ammonium tosylate, wherein, R1=xe2x80x94OCH3; R2=xe2x80x94H; R3,R4=CH3; n=3; R5=xe2x80x94Cl12H25; R7=xe2x80x94CH3 is described.
In another aspect the invention relates to a process of making a quaternary ammonium salt of cinnamidoalkylamine Formula I, 
wherein
R1 is a substituent, selected from H, halo, xe2x80x94OH, xe2x80x94NH2, xe2x80x94NO2, xe2x80x94OCH3, xe2x80x94N(CH3)2, alkyl groups containing from 1 to 6 carbon atoms, alkoxy groups containing from 1 to 6 carbon atoms, alkylamino or N,N-dialkylamino groups containing from 1 to 6 carbon atoms;
R2 is selected from hydrogen, alkyl group containing from 1 to 12 carbon atoms;
R3 and R4 are independently selected from benzyl, alkyl group containing from 1 to 12 carbon atoms,
n is an integer from 1 to 6;
R5 is selected from an alkyl group containing from 8 to 22 carbon atoms; alkenyl groups containing from 8 to 22 carbon atoms;
R7 is selected from bromo, chloro, nitro, methyl and ethyl groups,
wherein the process a compound of Formula II is reacted with a compound of Formula III to give an intermediate of Formula IV, the intermediate of formula IV is quaternised with a compound of Formula V, wherein, R1, R2, R3, R4, R5, R7, n are same as in Formula I and R6 of Formula II is selected form xe2x80x94OH, Clxe2x88x92 or xe2x80x94O(CH2)pCH3 with p=0 to 3 to provide the compound of formula I. 
According to a further aspect of the present invention there is provided skin care, hair care and fabric care formulations containing novel organic-soluble cinnamidoalkylamine quaternary ammonium compounds of Formula I and conventional active ingredients of skin and hair care products.
The unique combination of substantivity to hair and skin, conditioning, strong UV absorption and water-insolubility of these quaternary compounds of cinnamidoalkylamines is very desirable for personal care products, especially for skin care applications.
The substantive UV absorbing compounds of the present invention are quaternary salts of cinnamidoalkylamines that are prepared by reacting lower alkyl ester of cinnamic acid or acid halides of cinnamic acid with an amino compound that is subsequently quaternised with substituted benzene sulphonate esters of fatty alcohols. The preferred compounds of the present invention are water-insoluble quaternaries of cinnamidoalkylamines.
In the process, the amidification reaction between a compound of the Formula II when R6=xe2x80x94OH or xe2x80x94O(CH2)pCH3 with p=0 to 3, with that of Formula III is carried out at from about 120xc2x0 C. to about 200xc2x0 C., under pressure from about 10 psi to about 100 psi, in the presence of a basic catalyst such as sodium methoxide, sodium hydroxide from 0.25% to 5.0% by weight of the reaction mass, to afford the intermediate compound of Formula IV. 
Preferred amount of such catalyst is 1.0% w/w of total reaction mass. The reaction is conveniently monitored by TLC or HPLC using UV detection. After the complete disappearance of cinnamic acid ester, the excess diamine is distilled off under vacuum.
Alternately, this reaction is carried out in the presence of a basic catalyst such as sodium methoxide, sodium hydroxide from 0.25% to 5.0% by weight of the reaction mass under atmospheric pressure, under blanket of nitrogen, with an arrangement for continuous selective removal of lower alcohol formed in the reaction.
Thus, the condensation reaction of one mole of cinnamic acid ester is carried with 1.0 to 3.0 moles of diamine at 120 to 200xc2x0 C., preferably at 180xc2x0 C., for 12 to 36 hours. The amines themselves can catalyse the reaction, however, the rates are found to be slower as compared with the bases like sodium methoxide and the like.
The same reaction can be performed using cinnamic acid in place of cinnamic acid ester at temperatures up to 200xc2x0 C. and pressures of 100 psi, keeping the same stoichiometry (1:1.0 to 3). The excess diamine serves as solvent for the reaction.
Cinnamic acid esters and amino compounds are selected that are liquid within the disclosed temperature and pressure range. This reaction generates lower alcohol that need not be distilled out.
The amidification reaction between a compound of Formula II when R6=xe2x80x94Cl in the presence of a solvent, is carried out with that of Formula III at room temperature in the presence of solvent. The compounds of Formula IV are synthesised by reacting acid chlorides of Formula II (1.0 mole) when R6 is xe2x80x94Cl with the diamines of Formula III (1.0 to 1.2 mole) at 20-50xc2x0 C. in an inert solvent like dichloromethane, ethylene dichloride, tetrahydrofuran and the like. 
The alkylating agents used in the present invention are fatty alcohol esters of substituted benzene sulphonic acids of Formula V, wherein, R5 and R7 are same as in Formula I. Compounds of Formula V are synthesised from fatty alcohols, either pure or a mixture, by reacting with benzene sulphonyl chloride or tosyl chloride and the like in the presence of a suitable base. This esterification is carried out in aprotic solvents like tetrahydrofuran, dichloromethane. Fatty alcohols used in the present invention are of natural origin (vegetable oils) and synthetic origin (Ziegler, Oxo process). Thus, they are both branched or straight chain alcohols, n-octanol, n-dodecanol and the like. The long chain alcohols with a degree of unsaturation like oleyl alcohol are also suitable for the present invention.
Quaternization of cinnamidoamines is carried out in solvents that include, dimethyl formamide, tetrahydrofuran, lower branched alkanols such as isopropanol, t-butanol and combinations thereof. Mixtures of these solvents can also be used. Solvents used are from 20 to 80% by weight of the reaction mass. The cinnamidoalkylamines (Formula IV, 1 mole) are N-alkylated with quaternising agents (Formula V, 1.0 mole) in the presence of suitable solvents preferably such as THF, isopropanol that govern temperatures at which the reaction is carried out.
The quaternisation reaction can be conveniently done in a pressure reactor as well as in an open system. The temperatures suitable for pressure reaction range from about 60-125xc2x0 C. with the pressures up to 50 psi. The pressures are governed by the amount of solvent and the temperature selected for the reaction. The conditions of reaction in an open vessel also get dictated by the choice of solvent. The reactions are usually carried out at boiling point or slightly below boiling point of the solvent employed. The resulting quaternary salts are obtained as concentrated solutions. The progress of the reaction is monitored by measuring the amount of unreacted alkylating agent by chromatography or by estimation of unquaternized amidoamine or by determining the active matter (the quaternised product) by two phase titration with anionic surfactant.
On Quaternization, the solvents are removed from concentrated solutions of quaternary ammonium salts to obtain solvent free pure compounds in the form of low melting solids.
Alternately, quaternisations can be carried out by directly reacting equimolar quantities of cinnamidoalkylamines of Formula IV with fatty alcohol esters of substituted benzene sulphonic acids of Formula V at from about 100 to 140xc2x0 C. for 4 to 24 hours without any solvent and in an inert atmosphere of nitrogen.
In these cationic compounds as shown in Formula I, the benzene ring of cinnamidoalkylamine contains a substituent (R1), preferably in para position and is selected from moieties such as xe2x80x94halo, xe2x80x94OH, xe2x80x94NH2, xe2x80x94NO2, xe2x80x94OCH3, xe2x80x94N(CH3)2.
Referring again to Formula I, the amido nitrogen is preferably either unsubstituted (R2 is hydrogen) or may contain a substituent, depicted in Formula I when R2 is selected from alkyl groups containing from 1 to 12 carbon atoms.
The quaternized nitrogen of compounds in accordance with the present invention contains substituents, R3 and R4 as depicted in Formula I, same or different, preferably selected from benzyl and/or alkyl groups containing from 1 to 12 carbon atoms.
The compounds of the present invention are cationic photofilters containing cinnamidoalkylamines moiety as shown in Formula I, in which n is an integer between 1 and 6, both inclusive. Preferred cationic photofilters in accordance with the present invention are compounds containing cinnamidoalkylamines in which n is 3.
The compounds of the present invention are cationic quaternary ammonium salts having cinnamidoalkylamines as shown in Formula I, in which the quaternary nitrogen bears the fourth group R5 that can be a fatty alkyl group containing from 8 to 22 carbons, both inclusive, and the alkyl chain can have unsaturation or branching.
Thus, the cationic photofilters of the present invention are formed by quaternising compounds of Formula IV by fatty alcohol esters of substituted benzene sulphonic acids of Formula V. The cationic photofilters of the present invention, also include an anion derived from quaternisation reactions. Given the quaternizing agents described above, the cationic compounds of the present invention will contain an anion, benzene sulphonate of Formula I, wherein, R7 is selected from bromo, chloro, nitro and methyl groups.
Another embodiment of the present invention relates to manufacture of a compound of Formula I, in which R1=para xe2x80x94OCH3, R2=xe2x80x94H, R3=R4=xe2x80x94CH3, R5=xe2x80x94Cl12H25 to xe2x80x94C18H37, R7=xe2x80x94CH3, counter anion=tosylate anion and n=3, from the compounds of Formula II (p-methoxy ethyl cinnamate, R1=xe2x80x94OCH3, R6=xe2x80x94OC2H5), Formula III (N,N-dimethylpropyldiamine, R2=xe2x80x94H, R3=R4=xe2x80x94CH3, n=3) forming an intermediate compound of Formula IV (p-methoxy cinnamidopropyldimethyl amine, R1=xe2x80x94OCH3, R2=xe2x80x94H, R3 and R4=xe2x80x94CH3) and Formula V (alkyl tosylate, R5=xe2x80x94C12H25 to xe2x80x94C18H37, R7=xe2x80x94CH3). The process of preparation of one such compound of Formula I is given in Example I.
Another embodiment of the present invention relates to manufacture of a compound of Formula I, in which R1=para xe2x80x94OCH3, R2=xe2x80x94H, R3=R4=xe2x80x94CH3, R5=xe2x80x94C12H25 to xe2x80x94C18H37, R7=xe2x80x94CH3, counter anion=tosylate anion and n=3, from the compounds of Formula II (p-methoxy cinnamoyl chloride, R1=OCH3, R6=Cl), Formula III (N,N-dimethylpropyldiamine, R2=xe2x80x94H, R3=R4=xe2x80x94CH3, n=3) forming an intermediate compound of Formula IV (p-methoxy cinnamidopropyldimethyl amine, R1=xe2x80x94OCH3, R2=xe2x80x94H, R3 and R4=xe2x80x94CH3) and Formula V (alkyl tosylate, R5=xe2x80x94C12H25 to xe2x80x94Cl18H37, R7=xe2x80x94CH3). The process of preparation of one such compound of Formula I is given in Example II.
The compounds of Formula I with substituents given in above two paragraphs are soluble in alcohols, glycols, mixtures thereof, mixtures of alcohols and water and mixtures of glycols and water. However, they are practically insoluble in water alone. Other suitable solvents can be polyethoxylated triglycerides, polyethoxylated fatty alcohols or ethoxylated silicones. These compounds are white to pale yellow solids with faint fatty odour. The substantive UV-B absorbers of the present invention are non-hydrolysable, non-irritant, non-mutagenic and compatible with commonly used cosmetic ingredients.
This invention provides compositions containing quaternary ammonium compounds of Formula I that are organic-soluble, UV-absorbing, conditioning and substantive to skin, hair and textile fibres. The hair care and skin care compositions containing compounds of Formula I can be solutions, dispersions or emulsions.
Lotions may be formed using compounds of Formula I, with or without one or more of the inert solvents like ethyl alcohol, isopropyl alcohol or propylene glycol, by combining with film forming polymers like proteins, polyvinyl pyrrolidone, polyvinyl alcohols and the like, film-forming starches and resins and the like.
Oil-in-water and water-in-oil emulsion can also be employed as vehicles for these compounds of Formula I to form lotions and creams. Conventional oil soluble UV-absorbing compounds like cinnamates, salicylates, p-aminobenzoates, benzophenones can be dissolved in oily phase of emulsion/lotions. The water-soluble sunscreens are dissolved in an aqueous phase of the emulsion and combined with the oily phase using a suitable cationic emulsifier such as stearylkonium chloride. Vegetable or mineral oils suitable for use as oil phase include mineral oil, petroleum, castor oil, sesame oil and the like. The quaternary ammonium compounds of the present invention are added to oily phase which is then subsequently emulsified with aqueous phase using an emulsifier like stearylkonium chloride or non-ionic emulsifiers like polysorbate-80, fatty alcohol ethoxylates and the like.
A preparation of cream hair conditioner of emulsion type having sunscreens of both the types, organic-soluble compounds of Formula I and water-soluble (organic-insoluble) sunscreens of our co-pending patent application (Indian Patent Appl. No. 903/Mum/2000 dated Oct. 6, 2000) is given in Example IV.
Perfumes, fragrances, anti-oxidants, preservatives, dyes colorants, insect repellents, fillers and suspended particulate matter, emollients, humectants, thickeners and the like may optionally be included in the sunscreen and tanning compositions of the present invention.
The sunscreen and tanning compositions of the present invention contain an effective amount of compounds of Formula I to prevent erythema. In general, an amount of about 0.5% to 10% w/w of the total composition is used.
For everyday use a sunscreen cream to protect the skin from both UV-A and UV-B radiation can be formulated as given in Example VI. The substantive UV absorbers, both water-soluble (xcex2,xcex2xe2x80x2-di(p-methoxy cinnamidopropyldimethyl ammonium chloride)ethyl ether) and water-insoluble (compounds of Formula I) can be conveniently incorporated at 2.0% each w/w of total composition. To cover UV-A range butyl methoxy dibenzoyl methane (Parsol 1789) is incorporated.
Face powder compositions of the present invention contain compounds of Formula I in an effective amount of 0.1% w/w to 0.5% w/w.
The hair care and skin care compositions of the present invention containing compounds of Formula I and may contain one or more ingredients selected form cosmetic agents such as surfactants, other sunscreen chemicals, after sun treatment materials, emollients, humectants, perfumes, anti-perspirants, moisturisers, color cosmetic materials, herbal extracts, occlusive oils and essential oils.
The compositions of compound with Formula I provide hair protection from UV radiation in addition to good conditioning effect. The hair protecting preparations can be formulated in the form of creams, lotions, tonics or gels.
The compounds of the present invention may also be formulated as hair care product such as shampoos, cream rinses, hair conditioners, hair dressing preparations, hair relaxers, hair coloring products and the like, capable of protecting hair from UV-B radiation.
The rinse-off preparations like shampoos, face washes and bathing bars contain 0.5 to 10% w/w of compounds of Formula I. It may be noted that these quaternaries are compatible with usual anti-dandruff, anti-microbial agents like Zinc pyrithione, Irgasan, Pyroctone. Hence, these compounds of Formula I can be incorporated in anti-dandruff shampoos.
Despite their cationic nature, the compounds of Formula I are completely compatible with anionic surfactants like sodium lauryl ether sulphate. The water insolubility and cationic nature does not effect transparency of transparent shampoo. The shampoo formulation thus made has been shown to deposit the quaternary compounds on hair (Example III).
Soap bars, both opaque and transparent/translucent can be formulated with compounds of UV-absorbing and conditioning compounds of Formula I. In soap bars, the cinnamidoalkyl quaternary ammonium compounds can be incorporated from 0.5 to 10.0% w/w, more preferably from 1.0 to 2.0% w/w of total composition. It may be noted that the compounds of Formula I in the following combi-bar formulation are compatible with anionic surfactants.
Furthermore, the compounds of Formula I when incorporated into a typical detergent powder or other household cleaning product compositions based on phosphate, carbonate or zeolite builders, very effectively impart anti-fading effect to colored fabric because of their substantivity. Typical detergent and household cleaning product compositions in accordance with the present invention include one or more surfactants, selected from anionic, cationic, nonionic and amphoteric detergents, alone or in combination. A typical detergent powder has been shown to deposit cationic photofilters of the present invention on fabric (Example VII).
The hair and skin protecting and detergent and household cleaning compositions of the present invention are also formed by admixing, dissolving the compounds of Formula I with other ingredients as in respective conventional composition. The preferred cosmetic compositions are solutions, dispersions or emulsions. The compositions contain an effective amount of one or more of UV-absorbing and conditioning compounds of the present invention to prevent erythema and darkening of skin due to solar damage.
In general, an amount of compounds of Formula I of about 0.5% to about 10% w/w and preferably between 2.5 to 8.0% w/w in a cosmetic composition of compounds of Formula I is useful particularly in personal hair and skin care products, sunscreens and tanning lotions. Leave-on preparations like hair oil may contain 0.01% to 2.0% w/w of compounds of Formula I. Typically, the ingredients are combined with mixing and heating if necessary until a uniform, homogeneous product is formed. With respect to the emulsion products of the present invention, the water-soluble and water-insoluble ingredients are mixed separately and combined with suitable emulsifier, preferably a cationic emulsifier, to form an emulsion.
A sunscreen cream for everyday use can be formulated with both water-soluble UV-B absorber (xcex2,xcex2xe2x80x2-di(p-methoxy cinnamidopropyldimethyl ammonium chloride)ethyl ether, Indian Patent Appln. No. 903/Mum/2000) and water-insoluble UV-B absorbers (compounds of Formula I) and any effective UV-A absorber like Parsol-1789 with silicone conditioners and Vitamins meant for skin care.
Unlike the hydrophobic photofilters from the prior art that are PABA based, the organic-soluble quaternary ammonium compounds of the present invention are based on cinnamidoalkyl moiety and absorb very strongly in UV-B region (e.g. molar extinction coefficient, xcex5 of p-methoxy cinnamidopropyldimethyllauryl ammonium tosylate was found to be 25,000 at xcexmax 310 nm). The cationic centre provides substantivity to skin, hair and fabric and the long alkyl chain provides the softening/conditioning effect.
The water insolubility and substantivity makes these molecules extremely attractive for external applications as against water-soluble molecules that may get absorbed through skin. In addition to these advantages, the compounds of the present invention are compatible with all commonly used cosmetic ingredients and are extremely stable. Despite being cationic surfactants, the compounds of the present invention are compatible with anionic surfactants and can be conveniently included in a transparent shampoo or a transparent bathing bar.